I've been watching the progress in these threads....
I agree, the billet method would be mighty expensive...
Casting would be much cheaper...especially since its aluminum. I would think the best route to go with these parts is use as many stock parts as possible, parts that are readily accesible.....
Like using a stock piston.. depending on the quench area, a flat top or dished piston would be nice to use, cheaper on the pockets....
and for those who wanted the absolute power from it.... they could alter their pistons to the specs they need.
I think if it costs a pile to get it to work, not many are going to even try to go that route....